Summary - 2.1.4 Enzymes

Methods for enzyme action What are
Reactions and activation
enzymes?
energy Lock and Induced sit
hey
catabolic reactions the active site the site
complementary that
-
break down larger molecules into smaller ones is
complementary active is not biological catalysts
anabolic reactions build up smaller molecules to the substrate specific to the to the substrate shape increase the reaction
-
into
larger ones -
enzyme rate of a


the
intracellular reactions -
take place inside cells once joined -enzyme-product complex enzyme performs a conformational ·globular proteins that are

extracellular reactions -
take place outside of cells formed -

temporary bonds formed with substrate
change to allow the substrate to bind solublehydrophobic
-
centre,
Activation
Energy ·products releasedfrom the active site ready for to the active site hydrophillic surface
->
withoutenzyme reaction
next this creates an
enzyme-substrate complex Intracellular enzymes found -




&
·the neededfor the inside cells
energy I ⑮rate 2 -
substrate
reaction occurs
forming the products -

e.g. catalase


& ame 8
reactants
released Extracellular
eithe
substrates/reactants to collide the the active
E
active site active site products are and enzymes-found
and to
form products site returns its original shape outside of cells-eg. trypsin
⑳
enzyme

produced by the pancreas




⑧ ⑧
->
products 2
I
ESC formed
enzymes lower metabolism
the activation -
of all different
0site
sum
·
-




sub sub
reactions in
organism
35
reaction cell

3
a or
energy of a
active

reaction 4 each
progress specificity

8
enzyme enzyme
enzyme only

8
-




active site
Umax the
- catalyses one reaction
-




⑤ ⑧
enzyme 4
Factors affecting enzyme activity rate where there enzyme 3

is most product products released
3
reaction occurs



Temperature formed
products formed
↓




achive
sit
active
site Cofactors
2
I. low hinetic
energy-less collisions -

sewer ESC formed Enzymes enzyme enzyme
cofactors -

inorganic, temporary, non-


:1
2. Optimum temp. -
max. number of ESC formed - Vmax ESC formed
occurs products released t
protein part -

eg. Zinc/iron
t reaction


changes
3
3. denature active site shape to
enzymes normal
returns
enzyme coenzymes organic, non-protein part
-
-




k no
-

longer complementary -
no ESC form
Inhibitors ↳
eg. vitamins
Temperature ( competitive prosthetic group-inorganic, permanent non-


Temperature coefficient(Q10) a measure -

of how much the rate
·
inhibitor binds to active site ⑮Strate
-
can't bind
to active
site
protein part eg. iron ion in -
haemoglobin (Fe2t)
doubles with a 100 temp. Increase Q,

↳
R2 R' - to help the
bonding
they sitin the active site
=
- =
inhibitor has a
complementary inhibitor
extreme temperatures cold-organisms 10° ->
c shape to the active site of the enzyme-substrate -
zinc ions the
x
eg. are
- +


active site

have enzymes that are less stable -
denature at smaller temp. changes ↳e
competes with the substrate enzyme cofactor inDNA polymerase
hot-thermophiles -
more stable
enzymes -
more resistant
to change at non-competitive
PH
2
higher temperatures
active site
inhibitor binds to the
Strate Investigating the effect of substrate
concentration on enzyme activity
denatured changes allosteric site


t
1.




↳
enzymes
-




l
shape no longer complementary no
-
ESC form
- ↳ causes conformational change -
active site

bonds enzyme METHOD:
↳
pH change affects in
tertiary structure in active site
allosteric
-
3
Zcm potato cylinder 5cm
2. Optimum pH-Vmax ↳ substrate
longer complementary grind with of water to make
site
paste
·
I no - a a
↳ inhibitor
10cm hydrogen peroxid
3. enzymes denatured place of into a test tube




·me
pH
end product inhibition ·use forceps to dip a
paper disc into enzyme suspension
renaturation-shape of enzyme returns to normal ↳ occurs when the
products drop the disc into hydrogen peroxide solution andmeasure the

after small pH changes interactions
enzyme shape more -

of a reaction act as inhibitors time taken for the disc to reach the bottom of the test


-
non-competitive
high pH-low conc. hydrogen ionschanges only functions within small - a
range to the enzyme that tube andrise again
low pH-high conc, hydrogen ions-less interactions, bonds break, enzyme shape changes catalysed its formation remove the disc and repeat for different concentrations of
substrate concentration
concentration
substrateenzyme more collisions
hydrogen peroxide
Independant variable concentration of hydrogen peroxide solution
-




Digestive enzymes
->

1. A substrate ESC rate PROTEINS


·~
formed
3 =
-
dependantvariable-time taken for disc to fall and rise
2. substrate conc. is the limiting factor STARCH made at salivary
pancreas
glands broken down to safely measures wear goggles be - and
careful with the
3. optimum substrate conc. broken down to maltose by amylase pepticles by protease hydrogen peroxide chemical hazard
·



enzyme conc
I -
-




substrate concentration
becomes limiting factor ·
maltose broken down to glucose peptides broken repeatability -
could repeat the experiment yourself and get the
·Umax -
all active sitesoccupied-rate of by maltase in small intestine down to amino acids same results

reaction only increasedif temp is 4 or more
enzyme
·

glucose absorbedinto blood by other proteases reproducibility -
someone else could
get the same results using the
is added in the digestive system Iabsorbed into blood same method